Preprint volume - SIBM

Pre-print Volume - Oral presentations
Topic 2: MARINE ORGANISMS AND ECOSYSTEMS AS MODEL SYSTEMS
M. BO, C.G. DI CAMILLO, M. BERTOLINO, P. POVERO 1 , C. MISIC 1 , M. CASTELLANO 1 ,
A. COVAZZI HARRIAGUE 1 , G.P. GASPARINI 2 , M. BORGHINI 2 , K. SCHROEDER 2 ,
G. BAVESTRELLO
1 DisMar, Università Politecnica delle Marche - 60131 Ancona, Italia.
m.bo@univpm.it
2 DipTeRis, Università degli Studi di Genova - 16132 Genova, Italia.
3 CNR-ISMAR - 19036 La Spezia, Italia.
THE MEGABENTHIC ASSEMBLAGES OF THE VERCELLI SEAMOUNT
(NORTH TYRRHENIAN SEA)
LE COMUNITÀ MEGABENTONICHE DEL VERCELLI SEAMOUNT
(MAR TIRRENO SETTENTRIONALE)
Abstract - The megabenthic assemblages of the Vercelli Seamount (North Tyrrhenian Sea) were studied
through ROV imaging from 60 to 500 m depth and a peculiar benthos zonation was observed. The
shallower rocky peak (60-100 m depth) hosted a very reach coralligenous community characterized, on the
top by the kelp Laminaria rodriguezii, by gorgonian assemblages on the southern flank and by sponges-soft
corals assemblages on the northern one. On the detritic bottom at the base of the peak, a very dense
population of the crinoid Leptometra phalangium was observed. On the edge of the detritic plain, around
180-200 m depth, a ring of the yellow scleractinian coral Dendrophyllia cornigera, mainly dead, was
recorded. The rocky slopes from 200 to 500 m depth, covered by a thick iron-manganese crust, were very
poorly colonized, mainly by encrusting sponges and serpulids. This research is the first detailed
investigation, through ROV imaging, of megabenthic communities living on a Mediterranean seamount,
representing therefore a study model for this peculiar ecosystem.
Key-words: benthos, seamounts, Tyrrhenian Sea, ROV imaging.
Introduction - Seamounts are considered to be hotspots of marine biodiversity being
characterised by rich benthic suspension-feeding communities of hard substrates
mainly composed of sponges, hydrozoans, scleractinians, antipatharians and
gorgonians providing habitat for numerous smaller, mobile invertebrates and hosting
an abundant and diversified ichthyofauna (e.g. Samadi et al., 2007). The Mediterranean
seamounts have been relatively well investigated from the geological point of view
(e.g. Zhuleva, 1988), but few data are available concerning the composition of their
megabenthic assemblages. An example is the description of a rich algal community and
the mollusc fauna on the top of the Amendolara Bank in the Ionian Sea by dredging
program (from 20 m depth) (Cecere & Perrone, 1988). Also the benthic fauna of the
top of the Eratosthenes Seamount (750 m depth) was studied by trawl and grab, to the
south of Cyprus, in the Eastern Mediterranean Sea (Galil & Zibrowius, 1998). Recently
ROV surveys were used to describe the coralligenous assemblages from 80 to 170 m
depth on four seamounts along the Spanish coast (Aguiliar et al., 2009). Moreover, the
biodiversity of several banks and shoals has been investigated along the continental
shelf of the North Tyrrhenian Sea, Sicily Strait, and the Aegean Sea. Studies focusing
on deep coral assemblages were made on some rocky shoals along the Calabrian
mesophotic zone (Bo et al., 2009) and on the white coral reefs found in the Ionian Sea
and mainly composed by the scleractinians Lophelia pertusa and Madrepora oculata.
The Tyrrhenian bathyal plain is spotted by at least 14 large and intermediate
seamounts. Their peaks are generally several hundred metres beneath the surface of the
sea, Vercelli Seamount however, together with Strabo Seamount, are shallow
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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